The invention relates to electrical timing arrangements and methods. Timing arrangements embodying the invention and to be described in detail below have enhanced fail-safe capability. They may therefore be used in circumstances in which it is important that premature production of an output signal (that is, before the end of the present timing period) is prevented.
One particular application in which embodiments of the invention may be used relates to the firing of the rocket motor of a rocket projectile ejected from the barrel of a gun such as a hand-held gun, for examPle an anti-tank gun. In one such application, the projectile is ejected from the gun with its rocket motor in the un-fired or un-energised state. It is required to fire the rocket motor only when a predetermined time has elapsed after the projectile has left the barrel of the gun. In this way, therefore, the rocket motor will not be fired until the projectile is some distance from the person holding the gun and the risk of injury to them is avoided It is of major importance to ensure that the timing of the firing is accurate. Premature firing may cause injury to the person holding the gun. Furthermore, the timing arrangement must be such that malfunction during long periods of storage will not cause false operation either during the storage or when the projectile is actually used.